The field of bioengineering involves the application of engineering principles to biological systems. The subdiscipline biomechanics deals with analyzing the response of living tissues to mechanical forces. Biomechanical studies of the cardiovascular system provide information on ventricular wall stress (force intensity), deformation, and blood pressure and flow. To date, this research has focused primarily on the mature cardiovascular system. Due to the rapid and simultaneous transformation of embryonic cardiovascular structure and function, the biomechanical environment likely influences growth, morphogenesis, and hemodynamic regulation in the embryo. Experimental results support the ability of the embryonic hearth to adjust myocardial mass functional demand, independently of morphogenesis. Little is known, however, about the quantitative biomechanics and regulation of cardiac development. Understanding this process requires an integrated experimental and computation approach. The long-term aims of the Bioengineering Core are (1) to provide the resources to develop and experimentally validate a biomechanical model of the embryonic heart for studies of the interrelation of mechanics, growth, and morphogenesis; and (2) to provide the resources for analyzing cardiovascular hemodynamic regulation in the embryo. The mathematical methods include solid modeling, finite element analysis, and Fournier analysis. The experimental methods, which explore cardiac mechanics in the white Leghorn chick embryo, include measures of global and local geometry, growth strains, ventricular pressure, and cardiac jelly pressure. Hemodynamic analysis is performed on clinically derived Doppler velocity waveforms. The specific aims of the Bioengineering Core are: Develop and support a computational system for mathematically describing the complex three-dimensional geometry of the embryonic heart. Develop a finite element code that includes the effects of complex- dimensional geometry, large deformation, anisotropy, muscle activation, and time-dependent volume and shape changes. Provide experimental data for model validation during normal growth and morphogenesis. Provide experimental data for model testing using protocols to modify ventricular pressure, degrade the extracellular matrix, modify the osmotic environment, and cut the dorsal mesocardium - all targeted at altering growth and morphogenesis. Provide signal processing and analysis of blood flow velocity waveforms using measures of heart-rate variability and Doppler velocity amplitude modulation. The Bioengineering Core provides all of the tools for the proposed engineering analyses. This combined computational and experimental approach is unique in the study of cardiac development.